Vapor generator



All@ 22, 1939. E. G. BAILEY r Al. 2,170,345

VAPOR GENERATOR l Orjinal Filed Deo. 18, 1955 13 Sheetsl-Sheet, 1

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Super/1mm- 242 .Super-heater Ouf Ervin G. Bai/e INVENTORS Perry E.Cassidy, 1PZ/p5 M Hard'gro Ve Aug. 22, 1939.

E.. G. BAILEY ET AL VAPOR vGENERATOR OrigialFiled Dec. 18, 1935 13Sheets-Sheet 2 IN V EN TORS z M-ardgmve.

le 'dj/Rd@ 5?* George D. Ebbets.

' 'ATTORNEYS Ervin G. 5m' Perry R Cass:

l l l I I l l i l I I Il NON , MSN

Aug. 22, 1939. E. G. BAILEY :r Al.

VAPOR GENERA'TOR Original Filed Dec.rl8, 1935 Make Up fram Ho Well Pumpl Fl 2 3 A lGaf.:

is aaser Pump Erl/in G. Edf/ey Perry R Caz/S51' dy, [Pa/ph MHardyray/eGeorge D Ebbes.

8%( www l5 Sheets-Sheet 5 from lower INVENTORS ATTORNEY.

Aug. 22, '1939. E. G. BAILEY ET AL VAPOR GENERATOR Original Filed Dec.18, 1935 l5 Sheets-SheetA 4 Figa Aug. 22, 1939. E. G. BAILEY Er AL.2,170,345

VAPOR GENERATOR Original Filed Dec. 18, 1935 `13 SheetS--Sheei'I 5 ErvinG Bai/ey, INVENTORS Perry R Cassidy, Pal/viz MHarcgroz/e Allg- -22, 1939E. G. BAILEY Er AL 2,170,345

VAPOR GENERATOR Original Filed Dec. 18, 1935 13 Sheets-Sheet 7 Ervin C5.az'ley INVENTORS ATTORNEY.A

llg- 22, 1939- l Eis. BAILEY r-:r AL 2,170,345

VAPOR GENERATOR 5 Original Filed Dec. 18, 1935 13 Sheets-Sheet 8 fri/n Gal'ley, INVENTORS Perry R. Cassidy ,Qa/7,1, Mfymdgmve Aug. 22, 1939.

E. G. BAILEY ET AL VAPOR GENERATOR original Filed nec. 18, 193s 13Sheets-Sheet 9 YIl' lll' (sgg .Sb S

canoe Il I ey. INVENTORS Perr- H Cassia /Pa/ hMHard rol/e y QQ# George'bbes. g

ATTORNEY.

Aug. 22, 1939.

E. G. BAILEY E1- AL 2,170,345

VAPOR GENERATOR 1 V- original Filed Deo. 18. 1935 15 sheets-sheet 1oF.2- 9

Ervin G. h/ey, INVENTORS ATTORNEY.

Aug. 22, 1939. E, G. BMLEY ETAL' 2,170,345

VAPOR GENERATOR -Original Filed Dec. 18, 1935 l5 Sheets-Sheet 11 [rv/'nG. Bai/ey, INVENTORS Aug. 22, 1939. E. G. BAILEY E1- AL 2,170,345

VAPOR GENERATOR Original Filed Dec. 18, v1935 13 Sheets-Sheet 12 Fig/3Er vin G. Bai/ey, INVENTORS Perry/R Casi/C254 Pa/,oh M/far'ro Ve Aug.22, 1939. E. G. BAILEY ET AL VAPOR GENERATOR 13 Sheets-Sheet 13 OriginalFiled Deo. 18, 1955 Erz/in G Bai/ey, INVENTORS Perry E. y, ,Qa/,MMHuff/grove ge D Ebbezfs. i ATTORNEY.

Patented ug. 22, 193.9

varon GENERATOR' Ervin G. Bailey, Easton, Pa., and Perry B. Cassidy,Short Hills, Ralph M. Hardgrove, Westfield, and George D. Ebbets,Kenilworth, N. J., assignors to The Babcock & Wilcox Company, Newark, N.J., a corporation of New Jersey Applieatien December 1s, 1935, serial'Ne.- 55,021

Renewed June 22, 1939 16 Claims.

This invention is a light weight, compact. forced flow steam generatorfor vmaking superheated steam at high pressure, and is of small liquidand heat storage capacity, but responsive to large and sudden variationsin steam demand withv substantially inappreciable time lag, thusrendering Ithe same suitable for variable speed motive power aplicationsin a range of sizes such, for instance, as are adapted to locomotive,ship and other classes of service, and especially for conditions whereweight and standby expense requirements have heretofore been bettersatisfied by the heavy oil engine than by former types of steamequipment.

Such a steam generator as fthe present invention, having small waterstorage and operated with 'a wide range combustion device, providesl acombination rendering practical extremely high heat release rates,withthe consequent ability to economically handle practicallyinstanltaneous load changes from. zero to maximum,` and vice versa. l

This generator, suitable for high steam pressures, has a small waterstorage capacity with relatively large heat-absorbing surface, whichnecessarily characterizes the construction as one incorporating smallbore tubes of great length and in multiple for the desired capacity.

The entire heating surface comprises small bore tubes, arranged insections, through which water and steam ow in a novel andA particularmanner, and in each section the multiple flow parts are connected inparallel between junctions which are of small diameter without requiringthe use of the usual steam and Water drums.

Y The vseveral sections, including economizer,

`steam generating, superheating, and air heating sections are arrangedin a novel combination, and

with certain new features of construction, each and all contributingtothe major objective.

One feature of the arrangement resides in the relation of -the smallbore tubular heating surface with reference, to the furnace, and to thepassage of the hot gases of combustion from the furnace to otherportions of the unit. The small that divide the space.

bore tubes are utilized to the fullest extent in the furnace walls,especially the tubes of Ithe steam generating section, to reduce heatstorage and provide a safe wall construction forthis intensely heatedspace. y

Another feature is that of insuring internal wetness of each of thesemultiple intensely heated steam generating tubes, arranged in parallel,by constantly maintaining an excess of water in them over and above thatwhich can be evaporated in a single passage therethrough to preventoverheating, and the removal of -the excess unevaporated` water` in amanner to carry away scale forming solids with such removed liquid, allas set forth in the copending application of E. G. Bailey Serial No.55,020 illed concurrently herewith.

The steam generator of the present invention is encompassed within flatwalls, and' the major part of the enclosed space is divided intosections by the arrangement of the portions of the small bore tubes toform, or to be disposed within, the outer boundary walls, and alsopartition walls This utilization of the small bore tubes of the heatingsurface to divide the whole space into sections arranged in a particularmanner, is a feature of this invention, and four such spaces areprovided, one being the upper part of vthe furnace for the flame of aburner located on the top for downward firing, and including about halfof the horizontal area; a second being an extension of the furnace, ata. lower level, and comprehensive of the whole area of the bottom orfloor, while the third and fourth are side by side parts of theremainder of the horizontal cross section beside and behind the rstfurnace partand for upwardly directing flowing gases from the furnaceextension in two parallel streams. y

The heat absorbing and steam generating capacitycf the generator isgreaterv per unit of vweight and space than is possible for usual steamresponding sizes for, the intended motive power service. These usefuland novel results are attained by means that insure the parts, at alltimes, against damage from overheating and which, of themselves, arefeatures of the present invention; and with them there are alsoincorporated features contributing to high efficiency, the whole beingpeculiarly susceptible to automatic control.

High eiciency is assured by steam generating tube heat absorption in thefurnace and in gas passage walls, cooperative with a high furnacetemperature attained by the use of some reradiating refractory betweenwall tubes, by the disposal of parts of the lengths of the long smallbore steam generating tubes across the path of the hot gases, and by therelative positions of the several sections of the heating surface withrelation to gas flow and gas temperatures.

Safety against, overheating is assured, for the steam generating tubes,by the maintenance of excess water through to the tube terminals, andfor the superheater tubes by positioning them behind a radiant heatscreen and by control of the fraction of the whole weight of furnaceexit gases passing over them, the remainder of the gas volume passingover steam generating and economizer tubes in the two parallel gasup-flow parts of the space behind the initial upper furnace down-firedflame space, after the gases have reversed their direction of flow 180over the whole bottom. As a contribution to high emclency the tubesdisposed across the upwardly directed gas passage are closely spacedcreating a high gas mass ow to increase the convection heat transferrate, and all the air for combustion is pumped into the furnace in amanner providing a sufficiently high furnace pressure to insure suchhigh gas mass flow.

The heat absorbing surface bounding the ow path for the water, wheresteam is being generated, as stated, is comprised of several long smallbore tubes between which the water is equally divided and arranged forthermal symmetry by equal exposure to the source of heat. At the end ofthis generating section there is a separator to divide water and steam.The saturated steam is then passed through a superheater. while theexcess water pumped through the tubes, in relation to the fuel fed andburned and for the purpose of preserving safety wetness and preventingscale deposit, is diverted out of the separator under regulatedseparator water level conditions, thus furnishing a control actuator inthe generator operation, as will be hereinafter set forth. From theseparator there is a normal continuous, and an additional regulatedspillover, or removal, of excess water limited as to maximum and minimumamount so that there is always being fed to and through .the economizerand steam generating sections more water than 'can be converted intosteam in the generating section, although the ratio or volume iof suchexcess water or spillover represents but a small part of the totalvolume of steam produced, and is suilcient, but no more than sufcient,to insure tube temperature safety by tube wetness and to carry oifscale-forming material.

In vapor generators of the character mentioned having small water andsmall heat storage with high furnace heat release and transfer rates,the Water feed must, of necessity, be continuous and at all timesproportioned to the steam produced, and at the 4same time take intoaccount the necessary minimum and the desired maximum spillover orremoval of excess water from the flow path. Furthermore, to accomplishthe wide range in heat release with substantially instantaneous responseto changes of conditions, and to perform the combustion processefficiently, there must be provided amethod and means for operating sucha vapor generator in accordance with varying conditions, and in a mannerto positively insure tube wetness throughout the total ow path uponstarting, and continued tube wetness throughout the generating sectionat substantially all times, and to further insure no overheating ofsuperheater tubes, preferably keeping the superheated steam temperatureconstant at all loads.

In vapor generators of such character one of the major considerations isthat of balancing, momentarily and continuously, the rate of heatrelease and absorption to the heat required to convert water intosuperheated steam, no matter how much or how suddenly the latter maychange while at the'same time proportionately, or equally, as may berequired, dividing the whole of the feed water between each of theseveral tubes working in parallel and similarly dividing the heatabsorbed by them. The construction provides for equal division of waterby the use of controlling resistances, and equal division of total heatabsorbed by each by locating each symmetrically with reference to thefurnace and flowing furnace gases so that each is similarly exposed toradiation and similarly swept by gases, under similar temperatureconditions, with resultant thermal symmetry throughout.

A further salient feature is the arrangement of the heating surfacerelative to the flow of the hot gases of combustion, which permitsdiversion of hot gases in a regulated manner, to adjust the heatabsorbed by the superheater as compared with the other convectionsurface, or vice versa', in order to regulate steam outflow temperature.

Additionally, the steam generator of the present invention is, asheretofore stated, of the type wherein more feed water is supplied toeach steam generating tube than is converted into steam in a singlepassage through each tube to the separator, and. the manner of recoveryof heat from such excess water withdrawn from the system at theseparator is a feature of the invention. The recovery of such heat fromthe spillover water according to the present invention, may be done bytransfer of its heat to one or more of the elements of combustion, andpreferably to the air pumped to the furnace for combustion. Cooperatingwith this air heater, as another feature of the invention, is theinterposition of an air-treating means wherein there may be a transferof heat to the air from water leaving the economizer accomplished in amanner suitable to` varying conditions of operation.

The following drawings, accompanying this specification, illustrateone'form which the lnvention may take in practice, and are similar toone which has been built and installed for operation:

Fig. 1 is a diagrammatic representation of a steam generating system ofthe present invention delineating the sequence of working fluid flowthrough the various sections of the path of flow of the working medium,together with the ow of hot gases of combustion over the heat absorbingsurface, without reference to geometry of shapes and position or tolevels.

Fig. 1a diagrammaticaily illustrates a forced present invention incombination with the requi-v n site control apparatus to insure thefunctioning of thel same automatically vwith the required safety andlexibility of which it is capable.

Fig. 2 is a perspective View of a generator according to the presentinvention with its auxiliaries.

Fig. 3 is a perspective view of the generator with the enclosing casingpartly broken away to indicate different sections of heating surface andthe arrangement of parts.

Fig. 4 is a somewhat diagrammatic perspective view partly cut awayshowing other parts of the arrangement of the heating surface.

Fig. 5 is a perspective view showing other parts of the arrangement ofheating surface, but with suflicient of the heating surface shown inFig. 4 broken away to ,indicate thereversal of portions of therespective tubes of one multiple set of flow path portions as theychange from one level to another.

Fig. 6 is a sectional view in vertical plane on the line 6-6 of Fig. 7.

Fig. '7 is a sectional view in the on the line 1--1 of Fig. 6.

Fig. 8 is a vertical sectional view on the plane of the line 8-8 of Fig.'7.

Fig. 9 is a horizontal transverse section on the .line 9 9 of Fig. '7.

Fig. 10 is a similar view on the line |0|0.of Fig. 7.

Fig. l1 is a fragmentary sectional View on the plane of the line II-IIof Fig. 9.

Fig. 12 is a fragmentary sectional view on the plane of the line I 2-I2of Fig. 11.

Fig. 13 isan enlarged detail elevation of the vertical plane vwater nowresistors, or distributors, and the manner of their arrangement.

Fig. 14 is a sectional view on the line ll-M of Fig. 13.

Fig. 15 is an enlarged sectional view on the line |5-l5 of Fig. 14.

Fig. 16 is a perspective view showing how one set of parallel horizontalwall tubes, at different levels, are bent to reverse the relative levelsof the same tubes of the set when the set as a whole changes level withrespect to gas ow, so as to bring the bends outside of the plane of thewall, and where they are not exposed to` heat, and where they are mostaccessible.

Figs. 17 and 18 are diagrammatic views showing the division of the majorspace bounded by flat walls into four divisions by three partitions.

In detail:

The vapor generator is diagrammatically shown in Fig. 1 in a mannerdelineating the multiple flow passages, or parallel Ccircuits, in theirrelation as to the direction of flow of working medium from feed waterentrance to superheated steam outlet, and as to the furnace and the owof hot gases, indicated thereon.

Referring to the diagram of Fig. 1 (and also with reference to Figs. 4and 5) the boiling section or steam generator portion comprises eightindividual flow passages, each continuous from water inlet to water andsteam outlet at, andv tangentially into, a separator 232. These eightpassages, which -are separate, long, small bore tubesl are designated'bythe letters A to H in-,

able water flow resistance 205. One type tlf re.

3 sister is shown in detail in Figs. '13 to 15, and its function is toadjust for difference in flow resistance and heat input as between therespec: tive passages, each of which `is initially designed to beapproximately equal in length and surface area, and so disposed as toabsorb equal amounts of heat from the furnace and the hot gases.

The tubes A to H- inclusive are disposed in an arrangement with respectto each other and to the source of heat such that there is a naturalbalancing of heat input to each individual passage, or equal division ofthe whole between them.A

This arrangement for equalizing the heat absorbed by each of the eightlongtubes in which steam is formed in parallel, and which is animportant feature of the invention, provides for positioning them sideby side in the walls of the furnace, gas passage, and partitions, as a.set progressing to successively higher levels, bending them aroundcorners, and also bending them otherwise, (as shown in Fig. 16) when thelevel is raised and the tube positions in the set are reversed; and italso provides for bending the tubes to form a transverse bank across thegas passage in a new way to not only cause each of the long bent tubesto absorb the same amount of heat radiantly, and by convection, but alsovprevents exposure of bends to heat at locations where, there may besteam pockets with consequent damage from high tube metal temperature.

, Access to individual'tubes is also provided in this arrangement. f

Where the tubes are disposed in 'the vertical furnace wall they arehorizontal and spaced apart approximately one tube diameter whichpermits of access and of adding any desired form of extended surface,such as is shown. for example in Figs. 11 and 12, but of importance alsoin that it makes possible refractory filling in the intertube spaceswhich acts as a reradiating surface invthe other in this flat band bentaround the corf ners.

Startingwith-the lowermostv position of the set of eight tubes A to H,which. are connected to the header 204 through the flow resistors 205,

these tubes are designated with A indicating the lowest, and disposed'in the order. named one above the other.

' After the set of eight tubes completes its circuit of the bottom ofthe unit boundary walls, it is then raised to a higherlevel (see Fig. 4)andv disposed in a horizontal flat transverse coil of return bend loopsextending the run width ef the unit and to approximately one half thedepth in the upflow gas passages IlI and IV behind the furnace I. Thetubes thus bent lie one over the other 'so that they are horizontally instaggered relation to eachother at successive levels. After thus formingone bank of horizontal staggered tubes leight tubes high, the eighttubes of the set are then bent to form another similar bank above therst one so that there is a bank of tubes across the gasl passages IIIand IV sixteen tubes high, the whole being above the furnace bottom adistance equivalent to the wall band eight tubes high, for the gases toflow upward from the bottom across the double tube bank. As the gasesare cooled by upward flow over the tubes it is necessary, forequalization of heat absorbed by each tube at successively higher levelsin the set, in each successively higherlevel of the set to change itsrelative position in the set each time.

the level of the set is raised. For example, the lowest tube of the setin the lowest position of the set is given the highest position in thenext higher position of the set, and again returns to the lowestposition in the third level of the set.

The arrangement of the tube grouping is further diagrammaticallyindicated by the letters A to H as below:

In this return bend loop vilatcoil transverse tube bank portion, thepile is self-supporting in that each coil rests upon the next adjacentone from top to bottom (see Figs. 3 and 4), but the coil lengths arevertically staggered, as to upflow of gases, except that, at the sidewalls of the unit and at the vertical partition wall dividing the upiiowgas passage into parts III and IV, Fig. 17, the tubes are in contact inthe same vertical plane to form substantially three (3) closed walls.

Portions of the length of alternate tubes in this transverse tube banksection are extended forwardly to crcumscribethe sides and frontboundaries of the furnace, while intermediatetubes are bent to liebetween the furnace I and the uplow gas passages III and IV (see Figs. 4and 5), whereby there is formed a partition between space I and spacesIII and IV (Fig. 17), to form a U-shaped gas path from burners throughoutlet flues, the rst leg being the flame space I, the bend the bottomspace II, and the second leg the spaces III and IV which have a tubewall partition between them.

Continuing upwardly to a fourth and a fth level, the same transversereturn bend coil arrangement for the eight tubes of the set is preservedfor a portion which extends approximately only half the width and depthof the unit in space III and`with the level of the tubes in each setagain reversed as the level of the set-is raised. There are four loopsforming the width of this portion, the balance of the width of the unitbeing reserved for the superheater, 'as will be described laten Rooftubes.

16 high half width bank of rc- HI turn bend loops.

16 high full width bank of return bend loops.

Complete circuit of bottomof furnace boundaries.

DIAGRAM B Beyond the transverse return bend coil tube bank section justdescribed the lset of eight tubes is bent to again circumscribe theboundary walls of the unit and to extend across the top to pro- .videroof tubes for the furnace (see Fig. 4)

where local bends of the tubes accommodate burner openings, as shown,for downward ring. In these positions'of the set the' relative positionsof the tubes are, of course, reversed with reference to their relativeposition in the set of the upper coils in the preceding looped portion.

It is to be understood that all of the steam is formed in horizontaltubes exposed to radiation, or swept by hot gases, whether the tubes liein walls or extend across the gas streams, while the flame and hotgases-pass iirst vertically downward from top to bottom, across thebottom and then vertically upward from bottom to top. Each long steammaking tube, while horizontal, is so bent and positioned as to be ondiierent levels for successive parts of its length, and the successionis always upward. In passing from one level to another the manner liquidgoes through conduit 203 to the inlet of accomplishing transposition orthe reversal of relative levels of tubes in the set, or band of eight,as the level of the set is raised,` is shown in Fig, 16, wherein eachtube bends outside of the plane of the wall; and these bends are such asto cause the flow to be always upward between the horizontal parts ofthe tube exposed to heat.

As all of the length of each of the steam making tubes exposed to heatis horizontal, and the general trend Iis upward for successive parts ofthe length of each tube from one level to a higher level, the waterentering at the bottom, and steam and water leaving at the top, steamwill be continually moving with the water and cannot form local steampocket zones that might overheat. 'I'hus an important feature of theinvention is the arrangement of horizontal tubes with generally upwardow exposed to heat in a vertical downward-fired furnace and rst gas passand a second vertical gas pass so as to prevent local overheating, when,as otherwise described, there is more water fed to each tube than can beevaporated.

While in the embodiment described we have divided the water into eightequal parts for eight steam making tubes, and arranged each tube toreceive equal amounts of heat by radiation and convection transfer, itwill be understood that the invention is not thus limited. We

. may use other thaneight vaporizing circuits, the

number varying with the size of the unit and with other conditions, butalways more than one.

' is the superheater 242 of substantially identical Furthermore, sincethe essential thing is assurance of wetness of steam delivered by each,the water may be unequally divided between them when at the same timethe heat absorbed by each is correspondingly and proportionatelyunequally divided by length or position with reference the furnace andhot gas iiow. y

Further, referring to the diagram of Fig. 1, and also to the diagramFig. 1* of the control, the water enters the system through the controlvalve I1 in the supply pipe to the feed water pump 289 driven by theauxiliary turbine 201, which also drives the air pump 288 and fuel oilsupply pump 290. Thefeed pump .289, which may be in duplicate,discharges water to the economizer 202, this being comprised of theprimary economizer section 202 and the secondary economizer sectionsi202il and 202D, each of -these being of the type shown in Fig. 3wherein vertically spaced horizontal headers are connected by horizontaltubes bent to form vertical lat return bend coils. Beneath theeconomizer 202" construction? Similarly constructed also are the primaryand secondary air heaters 208 and 201, respectively, but these mayadvantageously have extended surface in theform of ins.

The iiowof working fluid through the generator is from the feed pump 289to the inlet header. of the economizer 202,`thence from the outletheader thereof to the inlet header of economizer unit 202a from theoutlet header of which it goes to the inlet header of economizer unit202 and then through the final outlet header 20| of the combinedeconomizer units; the-interconnections between the units have no specialconstruction except that they are in duplicate and enter, as

' shown, intermediate the ends of the headers,

and hence they are not designated by reference character since theircourse is clearly indicated in the drawings.

From the economizer outlet header 20| the header of the secondary airheater un-it 201, and from the outlet header oi' which it passes to themanifold 204 serving the resistors 205 in each of the eight tube iiowpassages of the steam generating section of the heating surface A to Hinclusive; the water entering the flow passages A to H then travelsthrough the generator surface in the order of surface arrangement aspreviously described, and as shown in the diagrams on Diagrams A and Bfinally emerging from the roof tubes through the tangential inlets tothe separator 232, said separator being illustrated in detail in thesaid copending application of EL G. Bailey Serial No. 55,020.

From the separator, where saturated steam and water are divided, theexcess water leaves the separator as spillover at the bottom throughfixed and variable spillover outlets 2 and 3 respectively, (see Fig.la). The spillover water, at saturatedv vapor temperature, passes to theinlet header of the primary air heater 206 where some of its heat isrecovered in the air being pumped to the fuel burners 4, and it thengoes to the feed water heater 354.

All the air for combustion of the fuel is pumped into the unit over theprimary and secondary air heaters 200 and 201 and passes through theburners 4 into the furnace where the flame burns downwardly toward thebottom, and here the gases are turned through 180 and travel upwardlythrough the two parallel gas paths passages III and IV separated by thedivision wall formed of the aligned tube lengths in the cnvection banks,and by a partition L which may be oi.' any suitable heat resistantmaterial, such as a metal or a non-metallic refractory body.

The air heater 201 has a special primary function in cooperation withthe resistors 205 in equalizing the distribution of water from theeconomizers to the eight steam making tubes. At times the water from theeconomizer may carry some steam and if mixed steam and water reaches thedistribution header 204, the equal division of both steam and waterbetween the eight tubes cannotbe effected. To prevent this, the steammust be condensed so that wat'er only reaches the header 204, and theair heater 201 may act as an air cooled condenser to eliminate steamfrom the delivery header whenever steam enters the inlet header with thewater.

'lhe details of the construction of the generator,lespecially the wallsand supports, are such that it is.. operatedmwith positive pressurethroughout the combustion chamber and gas paths in a manner similar tothat described in the Bailey pending patent application lhereinbeforereferred t0, all of the air for completecombustion being pumped into thesystem.

There is rstly the pile of tubes wherein the combustion chamber I isformed of boundary tube lengths which are studded as shown in Figs. 11and 12 in the manner of the invention set forth in the pendingapplication of E. G. Bailey, Ser. No. 39,010, iiled June 3, 1935, andHarter et al. Patent, 2,077,410, the studs being indicated as four rows300, 30|, 302, 804 at the rear of the exposed heat absorbing surface 305of each tube and embedded in refractory material 306.' 'Ihe entiregenerator is surrounded by a coveringl of two layers oi insulatingmaterial, one of them, 801, capable of withstanding high temperatureandthe other 308, outside, being such, for in stance, as magnesia andwhich has applied thereto a protective metal casing 309. The entirestructure is stabilized by upright columns 3|0 and angles 3| I togetherwith transverse members 3I2 and 3|3 which form asuitable frameworkthrough being connected in any well known manner as, for instance, bywelding. The side panels 309 of metal have stiieners 3I4 and 3|5 appliedthereto; the whole being arranged to resist destruction or leakage fromthe positive pressure maintained on the inside and which is greater thanthe existing pressure on the Outside.

Within the enclosed structure just described there are dependentsupports 3|6 and 3|`| which are in the nature of tension rods secured tothe tubes of the economizer sections and the superheater which supportthe same from above through carrying members 3|8 and 3|9 respectively atthe inner wall or divisionbetween the furnace chamber and gas paths. Thesupporting member 3I9 is carried bythe lower end of strips 320 which arealso dependent from the support 3|8. At the outer wall end the tubeloops are supported one from the other as indicated at 32| from theirupper headers.

The economizer 202 is similarly supported by members 322 at one sideadjacent the headers, and by hanging members 323 and 324 having rods 325and 326 respectively hooked over the lower ends of members 321 dependentfrom the cross beam 328, and the tubes of the economizer are. of course,enclosed within walls similar to those of the main portion of thegenerator.

At the top and to one side of the boiler assembly is an enclosure 329carried on. beam extension 330 and supporting the primary and secondaryair heaters 206 and 201 which receive their air at the entrance 208`from the air pump 288 and deliver it to the windbox 33| across the topof the furnace chamber and through which there are burner openings 332receiving the burners 4 delivering between the roof tubes which aredeformed, as shown in Fig. 4, and into the furnace I. Vanes 333 arelocated to guide the air where the flow turns at right angles to enterthe windbox 33|, and a damper 334 operating upon the spindle 335 from alever 336 regulates the ow of air from the air heaters to the burners.The windbox of the furnace is isolated from the waste gas outlet flowthrough the economizer by a partition 331 secured to a beam 338 whichtogether with the casing of the generator furnishes support for twoseries of dampers M and N (designated at 83 in Fig. 1a) each of whichconsists of the damper elements 339 carried on spindles 340 to which areattached levers 34|, the levers being secured together in groups M and Nby the damper bars 342, and, in turn, each group being secured to theother for operation in such a manner that either one group or the otheris open or closed, but never are both in the closed or open positionsimultaneously. This damper arrangement, by reason of the dividing wallin the path of the gases between passages III and IV, Fig. 18, isenabled, by proper manipulation, to pass all of the gases of combustionthrough the gas passage IV to sweep the economizer 202, if the group ofdampers N is closed and M open, or by closing the group vof dampers Mand opening those designated as N, all of the gases may be passedthrough gas passage III to sweep the superheater 242 and economizer 202,or by intermediate positions the amount passing over each may' beregulated to adjust the superheat temperature.

With the foregoing it will be Observed 'that the arrangement anddisposition of the heating surface, to'equalize heat received by each ofthe eight tubes of the steam generating set, is such thatthermal-symmetry is attained throughout the generator, and with itequalization of water supply results in equalizing of quality of steam-as to moisture in the superheater, and with this arrangement there isthen provided a control mechanism illustrated in Fig. 1a for operatingthe generator.

In connection with the operation of the generat'or it must be rememberedthat steam delivery to the prime mover, or throttle position on thesuperheater steam pipe, will be the means which will determine theoutput or rate of steam generation.

Also, with small liquid and heat storage and high heat releasecapabilities, the feed water supply must of necessity be continuous andat all times proportioned to steam outow, at the same time taking intoaccount the desired diversion of gases for superheat purposes, and ofliquid from ithe flow path at the separator and with maximum and minimumlimit of quantity, and there must also be provided means which willrender the generator instantaneously responsive to varying conditions ofrate of generation as to magnitude or suddenness of .changes whilemaintaining a high degree of eiiciency for all conditions within itsrange of operation from zero capacity upward while insuring safety ofoperation.

In Fig. la there is shown a diagram of a method and apparatus contr.lling the functioning of a boiler of the charac r described cooperatingwith it to insure the fulfillment of its capabilities, and which is thesubject of a separate application Ser. No. 55,023 iiled concurrentlyherewith in the name of Paul S. Dickey.

Considering the type of boiler the steam-makying section of which, asbefore stated, is comprised of separate long small bore tubes connectedin parallel between suitable headers or junction connectors andreceiving Water at one end and delivering a mixture of steam and waterat the separator, and subsequently delivering only superheated steam atthe outlet while discharging from it the excess water delivered to theseparator, the operation of the generator is as follows:

The water from the economizer header 20| is delivered to the header 204,from which the water is distributed to the generating section comprisingthe eight tube circuits A to H receiving their water through owresistors 205. Each of these flow resistors, as shown in Figs. 13 toinclusive, has a connecting portion 343 taking water from the manifold204 through the coupling 344 then through a long small bore coil 345which imposes a greater flow resistance or pressure drop than thepressure drop through the particular circuit A to H to which it isconnected. The length of each particular resistor coil of given bore 345is calculated for each circuit A to H so each will receive the samefraction of the total amount of water at all times. 'I'he ends of thesecoils 345 are coupled as at 346to the base 341, forming a cap welded asat 348 to' the end of the circuit A to H supplied by the resistor. Thebase 341 carries a ring 349 Welded thereto and which has spun thereoverthe end 350 of a Sylphon 35|, the other end of which is spun over asimilar collar 352 screwed into the., plate 353 of the furnace casing,and there is thus provided a gas-tight connection between the fuinacecasing andthe resistors [which permits off-,relative A. expansion andcontraction of the exible con- 'nected parts. From the resistors 205equally dividing the water, such liquid in each tube travelssuccessively through the. lower furnace wall portions, the convectionbank portions, the

l'partition wall portions, the upper furnace wall portions, and the rooftube portions of the length of the tubes in the order named, and finallydischarges from the roof ends of the tubes to the separator 232. Fromthel separator the excess water, as spillover, passes through the fixedoutlet orifice 2 and the variable outlet oricel vto the primary airheater 205 and thence to the open feed water heater 354, vented as at355, where it serves to commingle with, and to heat, incoming feed waterdelivered by the pipe 355 to the booster pump 351, and then through astrainer 358. to a battery of two feed pumps 288 driven by the auxiliaryturbine 281, which also drives the air pump 288 and the fuel oil pump290, all of which elements have been indicated diagrammatically-in Fig.la.

Referring now particularly to the diagrammatic illustration of Fig. 1*,the ow path from feed water entrance to superheated steam outlet hasbeen indicated as a single sinuous tube with a separator intermediately.Water is supplied to the economizer section 202 through a pipe II fromthe pump 289, which, as illustratedin Fig. 2, is a positive displacementpump, the delivery of which is closely proportioned to its speed, butmay be of any suitable type.

From the economizer section 202 the liquid passes to the steam making orgenerating section, the air heaters having here been omitted from thediagram for the purpose of making a lclearer diagram, inasmuch as airheating is not involved in the control. From the generator section thewater and saturated steam discharge together to the separator 232. Fromthe separator saturated steam passes through the superheater 242,leaving by the conduit 244 connected to the main steam turbine I2illustrative of any vapor utilizing device of prime mover. 'I'heproducts of combustion successively passA the generating section, thesuperheater and the economizer and may contact a part or all of theconvection surface as will be hereinafter referred to, depending uponthe position of the damper groups M and N.

An auxiliary turbine 281 drives the feed water pump 289, the air pump288, and theefuel oil supply pump 290. These elements are all driven bythe same shaft though they may be at diil'erent initial speeds, thenecessary gear reductions or driving mechanismbetween the severaldevices not being illustrated. 'I'he quantity of feed water is verynearly proportional to the speed of the feed pump. A

The rate of fuel oil supply to the burners I is primarily controlled bythe speed of the oil pump 290, but -the supply of oil is furtherregulated bythrottling of the regulating valve I3 located in the pipe 5;therate of ow. in the pipe 5 is continuously measured by the meter I4.

The rate of supply of air to support combustion is primarily determinedby the speed of the blower 288, but is further under control of thedamper I5 positioned in the conduit 1 at the outlet of the blower, sincethere must be adjustment of delivery to maintain the proper fuel-airratio in view of the fact that the blower is not a positive displacementpump as is the case with the fuel and water pumps. 'I'he rate of supplyof air is continuously measured bya flow meter I8.

The rate of supply of `liquid under pressure through the conduit II iscontrolled by the speed of the pump 289, but is further influencedthrough the position of the regulating valve I1 at the suction side ofthe pump and by the regulating valve I8 in the by-pass around the pump.

'In the operation of such a vapor generator certain variables aremeasured, indicated and utilized as the basis for automaticallycontrolling the supply of liquid throughout, and the supply of elementsof combustion to the heating furnace.

The control system, details of which are shown in said copendingapplication of Paul S. Dickey, Ser. No. 55,023, is as follows:

At I9 .there is indicated a pressure responsive device such as a Bourdontube connected to the conduit 2 and provided with an indicating pointer20 cooperating with an index 2I for advising the instantaneous value ofthe steam outilow pressure. At-22 is a temperature responsive device,such as a Bourdon tube, forming part of a temperature sensitive systemadjacent the conduit 2 and having an indicatorpointer 23 adaptedtocooperate with an index 24 for advising the instantaneous value of thesteam outflow .temperature and regulating the position of the superheatcontrol dampers at 83 (M and N).

As an indicator of generator output there is a iiow meter 18 connectedto the conduit 244 across an orifice or other restriction 19. 'I'hisflow meter is adapted to vertically position a pilot I3 to vary an, airloading pressure effective upon the relay 41 oportional to the steamoutflow.

The Bourdon tube 22 positioned responsive to variations in steam outilowtemperature is adapted to vertically position a pilot stem for varyingan air loading pressure through thecon- Gnection 8I- upon a pneumaticactuator 82 for positioning a set of dampers 83.which may correspond tothe groups of dampers M and N of Figure 8. Thesedampers, as previouslystated, are so located relative to the fluid path through the vaporgenerator and relative to control of gas ilow that they control `theheat absorption of different portions of the steam generator flow pathand thus control the steam outflow temperature.

29 Vrepresents means responsive to water level within the separator 232and onstitutes a pressure casing enclosing a mercury U-tub connectedacross the vertical elevation of the separator. Afioat is adapted toriseand fall with the surface of the mercury in one leg and to thuscause a positioning of a pointer 30 relative to an index 3| to advise-the instantaneous value of water level within the separator.

The flow meter indicated in general at I4 for providing a measure of the'rate of supply of fuel to the furnace may be of such a type as isdisclosed in the patent to Ledoux, No.'1,064,748. Such a meter is adifferential pressure'responsive device adapted to correct fornon-linear relation between differential pressure and rate of flow, tothe end that angular positioning of a pointer 32 relative lto the index33 is by increments directly proportional to increments of rate of flow.There is illustrated by dottedlines within the flow meter I4 the outlineof the internal construction wherein is a liquid sealed bell havingwalls of lmaterial thickness and shaped as described and supply of airfor combustion is similar to the

